1 /*

     2  * Copyright (c) 2013, 2016, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_G1_G1BIASEDARRAY_HPP

    26 #define SHARE_VM_GC_G1_G1BIASEDARRAY_HPP

    27 

    28 #include "memory/allocation.hpp"

    29 #include "memory/memRegion.hpp"

    30 #include "utilities/debug.hpp"

    31 

    32 // Implements the common base functionality for arrays that contain provisions

    33 // for accessing its elements using a biased index.

    34 // The element type is defined by the instantiating the template.

    35 class G1BiasedMappedArrayBase VALUE_OBJ_CLASS_SPEC {

    36   friend class VMStructs;

    37 public:

    38   typedef size_t idx_t;

    39 protected:

    40   address _base;          // the real base address

    41   size_t _length;         // the length of the array

    42   address _biased_base;   // base address biased by "bias" elements

    43   size_t _bias;           // the bias, i.e. the offset biased_base is located to the right in elements

    44   uint _shift_by;         // the amount of bits to shift right when mapping to an index of the array.

    45 

    46 protected:

    47 

    48   G1BiasedMappedArrayBase() : _base(NULL), _length(0), _biased_base(NULL),

    49     _bias(0), _shift_by(0) { }

    50 

    51   // Allocate a new array, generic version.

    52   static address create_new_base_array(size_t length, size_t elem_size);

    53 

    54   // Initialize the members of this class. The biased start address of this array

    55   // is the bias (in elements) multiplied by the element size.

    56   void initialize_base(address base, size_t length, size_t bias, size_t elem_size, uint shift_by) {

    57     assert(base != NULL, "just checking");

    58     assert(length > 0, "just checking");

    59     assert(shift_by < sizeof(uintptr_t) * 8, "Shifting by %u, larger than word size?", shift_by);

    60     _base = base;

    61     _length = length;

    62     _biased_base = base - (bias * elem_size);

    63     _bias = bias;

    64     _shift_by = shift_by;

    65   }

    66 

    67   // Allocate and initialize this array to cover the heap addresses in the range

    68   // of [bottom, end).

    69   void initialize(HeapWord* bottom, HeapWord* end, size_t target_elem_size_in_bytes, size_t mapping_granularity_in_bytes) {

    70     assert(mapping_granularity_in_bytes > 0, "just checking");

    71     assert(is_power_of_2(mapping_granularity_in_bytes),

    72            "mapping granularity must be power of 2, is " SIZE_FORMAT, mapping_granularity_in_bytes);

    73     assert((uintptr_t)bottom % mapping_granularity_in_bytes == 0,

    74            "bottom mapping area address must be a multiple of mapping granularity " SIZE_FORMAT ", is  " PTR_FORMAT,

    75            mapping_granularity_in_bytes, p2i(bottom));

    76     assert((uintptr_t)end % mapping_granularity_in_bytes == 0,

    77            "end mapping area address must be a multiple of mapping granularity " SIZE_FORMAT ", is " PTR_FORMAT,

    78            mapping_granularity_in_bytes, p2i(end));

    79     size_t num_target_elems = pointer_delta(end, bottom, mapping_granularity_in_bytes);

    80     idx_t bias = (uintptr_t)bottom / mapping_granularity_in_bytes;

    81     address base = create_new_base_array(num_target_elems, target_elem_size_in_bytes);

    82     initialize_base(base, num_target_elems, bias, target_elem_size_in_bytes, log2_intptr(mapping_granularity_in_bytes));

    83   }

    84 

    85   size_t bias() const { return _bias; }

    86   uint shift_by() const { return _shift_by; }

    87 

    88   void verify_index(idx_t index) const PRODUCT_RETURN;

    89   void verify_biased_index(idx_t biased_index) const PRODUCT_RETURN;

    90   void verify_biased_index_inclusive_end(idx_t biased_index) const PRODUCT_RETURN;

    91 

    92 public:

    93    // Return the length of the array in elements.

    94    size_t length() const { return _length; }

    95 };

    96 

    97 // Array that provides biased access and mapping from (valid) addresses in the

    98 // heap into this array.

    99 template<class T>

   100 class G1BiasedMappedArray : public G1BiasedMappedArrayBase {

   101 public:

   102   typedef G1BiasedMappedArrayBase::idx_t idx_t;

   103 

   104   T* base() const { return (T*)G1BiasedMappedArrayBase::_base; }

   105   // Return the element of the given array at the given index. Assume

   106   // the index is valid. This is a convenience method that does sanity

   107   // checking on the index.

   108   T get_by_index(idx_t index) const {

   109     verify_index(index);

   110     return this->base()[index];

   111   }

   112 

   113   // Set the element of the given array at the given index to the

   114   // given value. Assume the index is valid. This is a convenience

   115   // method that does sanity checking on the index.

   116   void set_by_index(idx_t index, T value) {

   117     verify_index(index);

   118     this->base()[index] = value;

   119   }

   120 

   121   // The raw biased base pointer.

   122   T* biased_base() const { return (T*)G1BiasedMappedArrayBase::_biased_base; }

   123 

   124   // Return the element of the given array that covers the given word in the

   125   // heap. Assumes the index is valid.

   126   T get_by_address(HeapWord* value) const {

   127     idx_t biased_index = ((uintptr_t)value) >> this->shift_by();

   128     this->verify_biased_index(biased_index);

   129     return biased_base()[biased_index];

   130   }

   131 

   132   // Return the index of the element of the given array that covers the given

   133   // word in the heap.

   134   idx_t get_index_by_address(HeapWord* value) const {

   135     idx_t biased_index = ((uintptr_t)value) >> this->shift_by();

   136     this->verify_biased_index(biased_index);

   137     return biased_index - _bias;

   138   }

   139 

   140   // Set the value of the array entry that corresponds to the given array.

   141   void set_by_address(HeapWord * address, T value) {

   142     idx_t biased_index = ((uintptr_t)address) >> this->shift_by();

   143     this->verify_biased_index(biased_index);

   144     biased_base()[biased_index] = value;

   145   }

   146 

   147   // Set the value of all array entries that correspond to addresses

   148   // in the specified MemRegion.

   149   void set_by_address(MemRegion range, T value) {

   150     idx_t biased_start = ((uintptr_t)range.start()) >> this->shift_by();

   151     idx_t biased_last = ((uintptr_t)range.last()) >> this->shift_by();

   152     this->verify_biased_index(biased_start);

   153     this->verify_biased_index(biased_last);

   154     for (idx_t i = biased_start; i <= biased_last; i++) {

   155       biased_base()[i] = value;

   156     }

   157   }

   158 

   159 protected:

   160   // Returns the address of the element the given address maps to

   161   T* address_mapped_to(HeapWord* address) {

   162     idx_t biased_index = ((uintptr_t)address) >> this->shift_by();

   163     this->verify_biased_index_inclusive_end(biased_index);

   164     return biased_base() + biased_index;

   165   }

   166 

   167 public:

   168   // Return the smallest address (inclusive) in the heap that this array covers.

   169   HeapWord* bottom_address_mapped() const {

   170     return (HeapWord*) ((uintptr_t)this->bias() << this->shift_by());

   171   }

   172 

   173   // Return the highest address (exclusive) in the heap that this array covers.

   174   HeapWord* end_address_mapped() const {

   175     return (HeapWord*) ((uintptr_t)(this->bias() + this->length()) << this->shift_by());

   176   }

   177 

   178 protected:

   179   virtual T default_value() const = 0;

   180   // Set all elements of the given array to the given value.

   181   void clear() {

   182     T value = default_value();

   183     for (idx_t i = 0; i < length(); i++) {

   184       set_by_index(i, value);

   185     }

   186   }

   187 public:

   188   G1BiasedMappedArray() {}

   189 

   190   // Allocate and initialize this array to cover the heap addresses in the range

   191   // of [bottom, end).

   192   void initialize(HeapWord* bottom, HeapWord* end, size_t mapping_granularity) {

   193     G1BiasedMappedArrayBase::initialize(bottom, end, sizeof(T), mapping_granularity);

   194     this->clear();

   195   }

   196 };

   197 

   198 #endif // SHARE_VM_GC_G1_G1BIASEDARRAY_HPP